Underground mining arch gateway system

ABSTRACT

This invention relates to a corrugated steel arch gangway system used in a method of mining an underground ore body. Commencing at the bottom of the ore body, successive horizontal cuts or layers are excavated, processed and backfilled with tailings from the processing. An arch shaped longitudinal horizontal portion of the gangway system is erected on the floor of the first lower cut and a plurality of first and second hollow extendible upward extending vertical portions are connected thereto by transverse horizontal portions. The horizontal portion of the gangway system is covered by a layer of backfill and then the first vertical portions or manways provide access from the horizontal portion to successive upward adjacent cuts which are mined and the ore is removed through the second vertical portions or millholes to a railway operating in the horizontal portion of the gangway system. As each cut is excavated, it is backfilled by a cemented hydraulic backfill following extension of the vertical portions. The longitudinal horizontal portion of the gangway system is constructed of a plurality of overlapping arch shaped sections, each of which is formed of a flat based member and first and second curved wall members. The members and the sections are initially positioned by being bolted together, and then securely connected by a plurality of self-drilling screws spaced along the joints.

United States Patent Madsen May 27, 1975 UNDERGROUND MINING ARCH GATEWAY[57] ABSTRACT SYSTEM This invention relates to a corrugated steel archgang- [76] Inventor: Jens Hilligso Madsen, 60 Brentwood y System used ina method of mining under Dr" Guelph Ontario, Canada ground ore body.Commencing at the bottom of the ore body, successive horizontal cuts orlayers are ex- [22] Filed: 1973 cavated, processed and backfilled withtailings from [21] APPL No: 344,926 the processing. An arch shapedlongitudinal horizontal portion of the gangway system is erected on thefloor of the first lower cut and a plurality of first and second [30]Apphcamm Pnoniy Data hollow extendible upward extending verticalportions Dec. 29, I972 Canada 161720 are connected thereto by transversehorizontal portions. The horizontal portion of the gangway system is[52] U.S. Cl. 61/45 R; 61/63 covered by a layer of backfill and then thefirst verti- [5 1] Int. Cl E21d 19/00 cal portions or manways provideaccess from the hori- [58] Field Of ear 61/45 zontal portion tosuccessive upward adjacent cuts 169 which are mined and the ore isremoved through the second vertical portions or millholes to a railwayoper- [56] References Cited ating in the horizontal portion of thegangway system.

UNITED STATES NT As each cut is excavated, it is backfilled by a ce-1,981,4l7 ll/l934 Kreutzer 52/86 x memed hydrfwlic backfi" F Q f of F2,185,532 [/1940 Waterman et aL 52/86 X vertical portions. Thelongitudinal horizontal portion 2,871,802 2/1959 Fishler 52/169 X of theg g y System is Constructed of a plurality of 3,034,607 5/1962 Haines52/86 X overlapping arch shaped sections, each of which is 3.0 9.835 /19Sundst m 52/l69 formed of a fiat based member and first and second3.057.! 19 10/ fl 52/86 X curved wall members. The members and thesections 3993-097 6/l963 Rosenfeld 52/169 x are initially positioned bybeing bolted together, and

3,159,? [2/1964 Rosenfeld 52/l69 X then Securely connected a plurality fSelf-{killing Primary ExaminerDennis L. Taylor screws spaced along thejoints.

10 Claims, 5 Drawing Figures PATENTEnmzvlars 3,885,395

sum 1 UNDERGROUND MINING ARCH GATEWAY SYSTEM BACKGROUND OF THE INVENTIONDESCRIPTION OF THE PREFERRED EMBODIMENTS Reference is first made to FIG.1 which partially This invention relates generally to a method of min- 5Shows a Corrugated Steel gangway System having ing wherein an ore bodyis progressively excavated and replaced by a pneumatic or hydraulicbackfill, and more particularly to a corrugated steel arch gangwaysystem and apparatus for carrying out such a method. 10

In the past, it has been known to mine ore bodies by progressivelyexcavating horizontal cuts and replacing them with horizontal layers ofpneumatic or hydraulic backfill. However, these previous methods haveutilized gangway systems constructed of a combination of heavy firtimbers, lighter timber lagging and a flexibie water tight membranecovering. Timber gangway systems have the gradually increasingdisadvantage that they are expensive in that suitable timber is becomingmore scarce and therefore costly and installation of the systems is timeconsuming and labour costs are continually increasing. In addition,timber gangway systems have the disadvantage that transportation of thetimber both in the mine and above ground is costly and inconvenient.Furthermore, the completed gangway systems present a substantialfirehazard, and the heavy cross timbers impede the flow of ventilatingair in the mine.

More recently, alternate methods using other materials have beenattempted, but these have proven to be unsatisfactory in that erectionof the gangway systems have been too time consuming and/or the erectedgangway system has not been sufficiently structurally stable.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to at least partially overcome these disadvantages byproviding a corrugated steel arch gangway system which may beeconomically manually erected and which is relatively structurallystable when erected.

To this end, in one of its aspects, the invention provides a gangwaysystem having a longitudinal horizontal portion formed of a plurality ofoverlappingly connected arch shaped sections, each section comprising aflat corrugated steel base member having first and second ends; a firstcorrugated steel curved wall member having upper and lower ends, thelower end adapted to be securely connected to the first end of the basemember; and a second corrugated steel curved wall member having upperand lower ends, the lower end adapted to be securely connected to thesecond end of the base member, the upper end adapted to securelyconnected to the upper end of the first wall member.

Further objects and advantages of this invention will appear from thefollowing description, taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective viewof a gangway system according to a preferred embodiment of theinvention;

FIGS. 2 to 4 are sectional views showing progressive steps in a methodof mining using the preferred em bodiment of the invention; and

FIG. 5 is a sectional view along line V-V in FIG. 3.

arch shaped longitudinal horizontal portion or gangway 12, a cylindricalfirst vertical portion or manway l4, and a cylindrical transversehorizontal connecting portion l6. In practice, the longitudinalhorizontal portion 12 of the gangway system 10 is erected in a mine toextend horizontally in the stope across the entire ore body, or in somecases may have junctions (not shown) to form a horizontal networkextending through a desired portion of the ore body. Normally, thegangway system 10 has additional vertical first portions 14 andtransverse horizontal portions 16 identical to those shown havingsuitable steps or stairs (not shown) lo cated at desired intervals alongthe length of the longitudinal portion 12 to form manways to provideaccess to successive upper horizontal cuts in the stope. In addition,similar second vertical portions 17 (shown in FIG. 5) are also spacedalong the longitudinal horizontal portion 12 and extend upwardlytherefrom to provide millholes. As shown, the longitudinal horizontalportion 12 is formed large enough to accommodate mine cars on track 18to carry ore received through the second vertical portions or millholes17 to conventional means for crushing the ore and removing it from themine for processing.

In more detail, the longitudinal horizontal portion 12 is formed of anumber of identical overlapping arch shaped sections 20. Each archshaped section 20 is in turn formed of a flat corrugated steel basemember 22, a first corrugated steel curved wall member 24 and a secondcorrugated steel curved wall member 26. Each arch shaped section 20 maybe erected by a crew of men by positioning the base member 22 onsubstantially flat floor 28 and then connecting the wall members 24, 26to it. The first wall member 24 is placed in an upright position and itslower end 30 is attached to a first upwardly flanged end 32 of the basemember 22 by one or two nuts and bolts (not shown) inserted throughco-operative bolt holes therein. The second corrugated steel curved wallmember 26 is then placed in an upright position, its lower end 36 issimilarly attached to a second upwardly flanged end 38 of the basemember 22 and its upper end 40 is attached to the upper end 42 of thefirst wall member by nuts and bolts 43. The arch shaped sections 20 maybe formed of 12 gage corrugated steel with a 2 h inch pitch and 1% inchdepth, and the wall members 24, 26 are normally two feet wide whichpermit them to be manually erected, although of course, mechanicalerection assistance devices may also be used. In this position, theerected arch shaped section 20 is sufficiently stable to support its ownweight, and additional base members 22 and wall members 24, 26 may beattached thereto to form additional arch sections 20 and therebylongitudinal horizontal portion 12. Adjoining arch shaped sections 20overlap at circumferential seams 44 and are initially attached togetherby bolts 46 passing through matched holes therein. Although bolts 46 areshown only as being common with some of the bolts 43 which hold themembers 22, 24, 26 of the arch shaped sections together, they may alsobe spaced along the circumferential seams 44.

As the longitudinal horizontal portion [2 is erected, the correspondingends of the members forming the arch shaped sections 20, and thecircumferential seams 44 between the arch shaped sections are securelyattached by a plurality of self-drilling screws 48 insertedtherethrough, spaced at approximately ten inch intervals. As may be seenthe upper ends 40, 42 of the first and second wall members 24, 26 form apeak 49, and the lower ends 30, 36 are located outside of the first andsecond ends 32, 38 of the base member 22. Although this structure initself assists in providing that the erected longitudinal horizontalportion 12 is relatively watertight, a suitable caulking compound mayalso be used if required. In addition the screws 48 may be provided withsuitable means such as neoprene gaskets which reduce leakage. Althoughthe longitudinal horizontal portion is structurally stable to withstandexternal forces when erected, it may be desirable from a safety point ofview to provide temporary internal support during introduction of thebackfill (as described below). This support may be provided byconventional timber or steel shoring temporarily positioned in thehorizontal longitudinal portion 12.

As described above, transverse horizontal portions 16 extend laterallyfrom the longitudinally horizontal portion 12 at desired intervals alongits length. Each transverse horizontal portion 16 is formed of a numberof overlapping cylindrical corrugated steel sections 50 which aresecurely connected together in a manner similar to that described abovein regard to the longitudinal horizontal portion 12. Each transversehorizontal portion 16 is closed at its outer end 52 by a bulkhead 54secured to the outermost cylindrical section 50. The second corrugatedcurved wall members 26 of several arch shaped sections 20 of thelongitudinal horizontal portion 12 are especially shaped to receive theinner end 56 of the transverse horizontal portion 16. Transitional steelplates 58 may be bolted, welded or fastened with self-drilling screws inplace to make the connection. However, it is pointed out that the amountof welding required must be kept to a minimum as underground welding ofgalvanized steel is undesirable due to the production of toxic gases.

The lower end 60 of the first vertical portion or manway 14 forms asimilar substantially watertight connec tion with the transversehorizontal portion 16. The first vertical portion 14 is also formed of aplurality of overlapping corrugated steel sections 62 which are securedtogether by nuts and bolts 43 and self-drilling screws 48 and extendsupward above the longitudinal horizontal portion 12. In the preferredembodiment shown, the longitudinal horizontal portion 12 isapproximately nine feet in height, and the upper end 64 of the firstvertical portion 14 extends to a height of approximately 15 feet abovethe floor 28 of the stope. The first vertical portion is cylindrical inshape with a diameter of approximately 6 feet, and has conventionalstairs located therein to provide access to the working level of themine.

Also extending upward from and spaced along the elongated horizontalportion 12 are second vertical portions or millholes 17. The secondvertical portions are also formed in sections and have upper ends 65which are extendible, but must be structurally stronger than the firstvertical portions 14 to withstand the passage of ore therethrough.Therefore, in the preferred embodiment, the second vertical portions 17are cylindrical in shape with a diameter of 6 feet and are formed of linch flat steel plate.

Although a gangway system 10 is shown with only a longitudinal portion12, manways 14 and millholes 17, it is apparent that similar portionsmay be connected in a similar manner to the system to form otherstructures such as ventialtion ducts.

Although the transverse horizontal portion 16 and the first and secondvertical portions 14, 17 are all shown as being cylindrical in shape, itis apparent that they may be formed of other shapes which are suitablefor use as manways and millholes.

In use, referring to FIGS. 2 to 5, a first lower horizontal cut 66 of anore body 68 is first excavated and the ore is crushed and removed to thesurface for processing in a conventional manner. Substantially fiatlevel floor 28 is formed by pouring a thin slab 69 of hydraulic backfillin the bottom of the first cut 66. A gangway system 10 according to theinvention is then erected on the floor 28 with the upper ends 64, of theseveral first and second vertical portions 14, 17 extending towards theceiling 70 of the first cut 66. As mentioned above, a railway track 18is normally laid on ballast 71 along the longitudinal horizontal portion12 to provide for transportation of the ore out of the gangway system 10to a crusher (not shown) and then through a vertical shaft (not shown)to a surface mill for processing.

Following erection of the entire gangway system 10 and after the variousmembers have been securely connected together using the self-drillingscrews 48, backfill 72 (see FIG. 3) is introduced into the first cut 66to a depth sufficient to cover the longitudinal horizontal portion 12but not sufficient to reach the upper ends 64, 65 of the verticalportions 14, 17. This backfill 72 is normally a cemented hydraulicbackfill consisting of tailings from the surface mill combined withcement in approximately the proportions of 32 to l, with an 8 to l mixused for the floors.

in some applications it is preferable to use alluvial sand or otheravailable material instead of or in combination with the tailings.Alternatively it will be apparent to those skilled in the art that apneumatic backfill formed from the tailings and/or other availablematerial may also be used. As mentioned, during introduction of thehydraulic backfill, caulking of the joints between the various membersof the gangway system 10 may be desirable to reduce leakage of thebackfill into the interior of the gangway system 10. Aftersolidification of the hydraulic backfill 72 to form a first consolidatedbackfill layer 73, ore is mined from the ceiling 70 of the first lowercut 66 and remove through the nearest millhole formed by verticalportions 17 to the railway operating in the longitudinal horizontalportion 12, to form a second horizontal cut 74 upwardly adjacent fromthe first horizontal cut 66. FIG. 5 shows that first and second verticalportions 14, 17 are longitudinally spaced along the length of thehorizontal portion 12 at desired intervals to provide sufficient accessto and allow economic removal of the ore from the second cut 74.

Following excavation of the second cut 74, the first vertical portionsor manways 14 are each extended towards the ceiling 76 of the second cut74 by adding several cylindrical sections 62. These sections 62 areerected and securely connected using nuts and bolts 43 and self-drillingscrews 48 as described above. Similarly, the second vertical portions ormillholes 17 are extended to approximately the same level. Additionalhydraulic backfill 72 is then introduced into the second horizontal cut74 on top of the first consolidated backfill layer 73 to a level nearthe upper ends 64, 65 of the extended vertical portions l4, l7 andpermitted to harden to form a second consolidated backfill layer (notshown). This process of alternatively excavating successive upwardlyadjacent ore cuts, extending the vertical portions and formingsuccessive consolidated backfill layers is repeated several times toremove a substantial vertical portion of the ore body throughlongitudinal horizontal portion 12. In the preferred embodiment shown,each cut is approximately twelve feet in height, and it has been foundeconomically desirable to erect another longitudinal horizontal portion12 rather than further extending the vertical portions l4, 17 followingexcavating and backfilling approximately ten successive cuts. This, ofcourse, may vary with conditions such as the type of ore in each case.

The initial introduction of backfill 72 around the longitudinalhorizontal portion 12 of the hollow gangway system exerts an upwardforce on the system 10 with the resulting danger of flotation of thesystem 10 in the backfill 72. It is apparent that flotation of anyportion of the longitudinal horizontal portion 12 in cemented hydraulicbackfill would create a very serious problem. Although this danger maybe overcome by securely anchoring the gangway system 10 to the floor 28,this solution is expensive and labour consuming. It has been found thatwhile a cylindrical shaped structure ofa sub stantial length may indeedfloat under these conditions, the present arch shaped structure issubstantially flotation resistent as the backfill 72 does not flowbeneath the flat base members 22 and approximately 80 percent of thecurvature of the curved wall members 24, 26 contributes to resistingflotation. The shape of the base members 22 and wall members 24, 26 hasthe added advantage that it permits nesting of the members duringtransportation prior to underground erection.

The present method has an advantage that it is not necessary that thegangway system 10 be designed to be able to withstand external loadingduring erection. ln addition, loading due to the introduction ofbackfill around the erected longitudinal horizontal portion 12 issubstantially uniformly applied from opposite sides and while temporaryshoring may be desirable (as mentioned above), it may be kept to aminimum. Furthermore, it has been found that following formation of twoor more backfill layers above the longitudinal horizontal portion 12,impact loading due to mining operation on successive upward cuts has noeffect on the longitudinal horizontal portion 12 due to bridging actionof the consolidated backfill.

Although the disclosure describes and illustrates a preferred embodimentof the gangway system, it is to be understood the invention is notrestricted to this particular embodiment.

What I claim is:

l. A gangway system manually erectable within confined undergroundopenings excavated during backfill mining to provide a horizontalnetwork for the progressive excavation of ore, comprising a plurality ofinterconnected elongated horizontal portions erectable underground in aconfined space in communication with a plurality of first and secondvertical portions, said horizontal portion being formed of a pluralityof overlappingly connected arch shaped sections comprising:

a. a flat corrugated steel base member having first and second ends andadapted to support mine cars on tracks,

b. a first corrugated steel curved wall member having upper and lowerends, said lower end adapted to be securely connected to said first endof said base member, and

c. a second corrugated steel curved wall member having upper and lowerends, said lower end adapted to first be securely connected to saidsecond end of said base member, said upper end adapted to then besecurely connected to said upper end of said first wall member,

said horizontal portions being adapted to be buried in a first layer ofbackfill after erection with said vertical portions projecting upwardtherefrom through said first layer of backfill to an upward horizontalore layer, said vertical portions being upwardly extendible to projectthrough successive upward horizontal backfill layers to successiveupward horizontal ore layers, said vertical portions being spaced toprovide access to said successive ore layers and for economical removalof ore downwardly therethrough to said horizontal network.

2. A gangway system as claimed in claim I further including a pluralityof hollow transverse horizontal portion extending laterally from thelongitudinal horizontal portions and the lower end of a correspondingone of the first vertical portion to communicate first vertical portionwith said longitudinal horizontal portion.

3. A gangway system as claimed in claim 2 wherein the transversehorizontal portions and the first vertical portions are formed ofcorrugated steel.

4. A gangway system as claimed in claim 3 wherein the transversehorizontal portions and the vertical por tions are cylindrically shaped.

5. A gangway system as claimed in claim 4 wherein the second verticalportions are cylindrically shaped and formed of one inch steel plate.

6. A gangway system as claimed in claim 1 wherein each of the firstvertical portions include vertically extending stairs.

7. A gangway system as claimed in claim 1, wherein the said ends of thebase member and the first and second wall members of each section areadapted to be overlappingly connected.

8. A gangway system as claimed in claim 1, wherein the said ends of thebase member and the first and second wall members of each section havematching bolt holes therethrough and are adapted to be initiallyoverlappingly positioned by nut and bolt engagement therein and thensecurely overlappingly connected by a plurality of spaced self-drillingfasteners extending therethrough.

9. A gangway system as claimed in claim 1 wherein adjoining arch shapedsections have circumferentially spaced matching bolt holes therethroughand are adapted to be initially positioned by nut and bolt engagementtherein and then securely overlappingly connected by a plurality ofcircumferentially spaced selfdrilling fasteners extending therethrough.

10. A gangway system as claimed in claim 1 wherein the base member andthe first and second wall members of each section are formed of 12 gaugecorrugated steel ofsubstantially a 2 inch pitch and a inch depth. k i

1. A gangway system manually erectable within confined undergroundopenings excavated during backfill mining to provide a horizontalnetwork for the progressive excavation of ore, comprising a plurality ofinterconnected elongated horizontal portions erectable underground in aconfined space in communication with a plurality of first and secondvertical portions, said horizontal portion being formed of a pluralityof over-lappingly connected arch shaped sections comprising: a. a flatcorrugated steel base member having first and second ends and adapted tosupport mine cars on tracks, b. a first corrugated steel curved wallmember having upper and lower ends, said lower end adapted to besecurely connected to said first end of said base member, and c. asecond corrugated steel curved wall member having upper and lower ends,said lower end adapted to first be securely connected to said second endof said base member, said upper end adapted to then be securelyconnected to said upper end of said first wall member, said horizontalportions being adapted to be buried in a first layer of backfill aftererection with said vertical portions projecting upward therefrom throughsaid first layer of backfill to an upward horizontal ore layer, saidvertical portions being upwardly extendible to project throughsuccessive upward horizontal backfill layers to successive upwardhorizontal ore layers, said vertical portions being spaced to provideAccess to said successive ore layers and for economical removal of oredownwardly therethrough to said horizontal network.
 2. A gangway systemas claimed in claim 1 further including a plurality of hollow transversehorizontal portion extending laterally from the longitudinal horizontalportions and the lower end of a corresponding one of the first verticalportion to communicate first vertical portion with said longitudinalhorizontal portion.
 3. A gangway system as claimed in claim 2 whereinthe transverse horizontal portions and the first vertical portions areformed of corrugated steel.
 4. A gangway system as claimed in claim 3wherein the transverse horizontal portions and the vertical portions arecylindrically shaped.
 5. A gangway system as claimed in claim 4 whereinthe second vertical portions are cylindrically shaped and formed of oneinch steel plate.
 6. A gangway system as claimed in claim 1 wherein eachof the first vertical portions include vertically extending stairs.
 7. Agangway system as claimed in claim 1, wherein the said ends of the basemember and the first and second wall members of each section are adaptedto be overlappingly connected.
 8. A gangway system as claimed in claim1, wherein the said ends of the base member and the first and secondwall members of each section have matching bolt holes therethrough andare adapted to be initially overlappingly positioned by nut and boltengagement therein and then securely overlappingly connected by aplurality of spaced self-drilling fasteners extending therethrough.
 9. Agangway system as claimed in claim 1 wherein adjoining arch shapedsections have circumferentially spaced matching bolt holes therethroughand are adapted to be initially positioned by nut and bolt engagementtherein and then securely overlappingly connected by a plurality ofcircumferentially spaced self-drilling fasteners extending therethrough.10. A gangway system as claimed in claim 1 wherein the base member andthe first and second wall members of each section are formed of 12 gaugecorrugated steel of substantially a 2 2/3 inch pitch and 1/2 inch depth.